Dead Arm Syndrome

Dead Arm Syndrome is characterized by sudden, sharp, or "paralyzing" pain when the shoulder is forcefully moved into external rotation while elevated, or when it is exposed to a direct blow. Because of pain and numbness, the patient is no longer able to perform a throwing motion with the same control and speed as before the injury. The condition is also known as recurrent transient subluxation of the shoulder.[1][2]

Shoulder position associated with Dead Arm Syndrome

There are two categories of Dead Arm Syndrome:

• Aware of subluxation: The patient is aware that the shoulder has partially dislocated.

• Unaware of subluxation: The patient is not aware that the shoulder has been partially subluxed but still experiences symptoms such as pain and numbness.

This condition often occurs during activities involving throwing or other demanding shoulder movements and may lead to substantial loss of function in sport or everyday activities.

Epidemiology and Etiology

Dead Arm Syndrome is usually associated with anterior shoulder instability and injury to the anterior labrum, most likely following subluxation of the humeral head. This causes transient traction of the brachial plexus during a forceful throw.[3] The syndrome may have several different causes. It commonly involves pathology of the rotator cuff or labrum. Shoulder instability or posterior capsular contracture may contribute to the development of Dead Arm Syndrome. Other possible causes include calcification in the glenohumeral joint, acromial bone spurs, impingement of shoulder ligaments, biceps tendinitis, microinstability, internal impingement, and SLAP lesions. Psychological factors may also contribute. The syndrome can occur during throwing, repeated forceful tennis serves, or work performed with the arm held under tension above shoulder height.[1][3] Symptoms may worsen when posterior rollback is reduced, causing anterior translation and increased internal impingement in the posterior shoulder.[4]

Dead Arm Syndrome occurs most often in young athletes aged 21–30 years or in individuals who have subjected the arm to forceful hyperextension with shoulder elevation and external rotation.[1] It is common in people participating in repetitive throwing sports because the arm is repeatedly rotated backward as far as possible (external rotation) to generate potential energy during the cocking phase before forward acceleration. The pain is thought to result from overstretching of the anterior shoulder capsule. This may allow the humeral head to translate anteriorly, causing impingement of structures at the front of the shoulder joint and resulting in pain and an inability to throw.

Differential Diagnosis

Dead Arm Syndrome is often misdiagnosed as other shoulder disorders or cervical conditions. However, several features distinguish Dead Arm Syndrome from other causes of shoulder dysfunction. It usually occurs in young athletic adults aged 21–30 years, has a characteristic history of forceful shoulder hyperextension, and is associated with a positive apprehension test with relocation.[1]

Examination

A positive apprehension test is a characteristic finding in Dead Arm Syndrome. The test can be performed with the patient standing or lying down. The shoulder is passively moved into maximal external rotation and abduction. An anteriorly directed force is then applied to the posterior aspect of the humeral head. The therapist applies pressure toward the anterior humeral head. The test is positive when the patient suddenly becomes apprehensive, reports shoulder pain, and feels that the shoulder is about to dislocate. If the apprehension test is not strongly positive, another cause of the shoulder dysfunction should be suspected rather than transient subluxation.[1]

Treatment and Interventions

Treatment for Dead Arm Syndrome includes physiotherapy similar to that used for shoulder instability and labral injuries. Surgery may be required to correct instability and repair damage to the glenoid labrum.[3] Once inflammation and pain have subsided, the patient can begin a return-to-throwing program, which takes approximately 4 weeks.[1]

Full range of motion (ROM) and flexibility should be restored before strengthening begins. Strengthening includes resisted internal rotation, external rotation, and shoulder abduction to strengthen the rotator cuff muscles that stabilize the humeral head. This program, which should be carried out for 3–4 months, may reduce pain and disability.[1][5][3] Rehabilitation of athletes with Dead Arm Syndrome should include the entire kinetic chain.[1]

In some cases, the condition progresses to a full clinical picture of posterosuperior impingement with development of a SLAP lesion. Surgical treatment may then be necessary.[6] SLAP lesions are repaired arthroscopically, and different types of SLAP lesions require different repair strategies.[7]

Sources:

1.  CR Rowe and B Zarins, Recurrent transient subluxation of the shoulder, J Bone Joint Surg Am. 1981;63:863-872.à

2.  Burkhart SS, Morgan CD, Kibler WB. Shoulder injuries in overhead athletes: the “dead arm” revisited. Clinics in sports medicine. 2000 Jan 1;19(1):125-58.

3.  Richard B. Birrer,Bernard A.. Griesemer,Mary B. Cataletto, M.D.Pediatric sports medicine for primary care, 2002, p348

4.  Donald H. Johnson, M.D, Practical orthopaedic sports medicine & arthroscopy, 2007

5.  Ho CY, The effectiveness of manual therapy in the management of musculoskeletal disorders of the shoulder: a systematic review, Man Ther. 2009 Oct;14(5):463-74. doi: 10.1016/j.math.2009.03.008. Epub 2009 May 21.

6.  Kibler WB. The role of the scapula in athletic shoulder function. Am J Sports Med 1998;26:325-337

7. OrthoInfo. SLAP Tears. Available at: http://orthoinfo.aaos.org/topic.cfm?topic=A00627